Emulating the fast-start swimming performance of the Chain Pickerel (Esox niger) using a mechanical fish design
Name
74817918-MIT.pdf
Description
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6.4 MB
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54d1b7818852482cd1331a50dd34b8bf
Author(s)
Watts, Matthew Nicholas
Advisor(s)
Michael S. Triantafyllou and Franz S. Hover.
Date Issued
2006
Publisher
Massachusetts Institute of Technology
Abstract
Mean maximum start-up accelerations and velocities achieved by the fast-start specialist, northern pike, are reported at 120 ms-2 and 4 ms-1, respectively (Harper and Blake, 1990). In this thesis, a simple mechanical system was created to closely mimic the startle response that produces these extreme acceleration events. The system consisted of a thin metal beam covered by a urethane rubber fish body. The mechanical fish was held in curvature by a restraining line and released by a pneumatic cutting mechanism. The potential energy in the beam was transferred into the fluid, thereby accelerating the fish. The fish motion was recorded and the kinematics analyzed while using a number of different tail shapes and materials. Performance of the mechanical fish was determined by maximum acceleration, peak and averaged maximum velocity, and hydrodynamic efficiency. Maximum start-up acceleration was calculated at 48 ms-2. Peak and averaged maximum velocity was calculated at 0.96 ms-1 and 0.8 ms-1, respectively. The hydrodynamic efficiency of the fish, calculated by the transfer of energy, was 11%. Flow visualization of the mechanical fast-start wake was also analyzed. The visualization uncovered two specific vortex-shedding patterns; a single and a double-vortex pattern are described.
Description
Thesis (S.M. in Oceanographic Engineering)--Joint Program in Ocean Engineering/Applied Ocean Physics and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2006.
Includes bibliographical references (p. 74-75).
Subjects
Joint Program in Ocean Engineering/Applied Ocean Physics and Engineering.
Mechanical Engineering.
Woods Hole Oceanographic Institution.
MIT Department
Joint Program in Ocean Engineering/Applied Ocean Physics and Engineering
Woods Hole Oceanographic Institution
Massachusetts Institute of Technology. Department of Mechanical Engineering
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